This invention relates to an outboard motor and more particularly to an improved cooling system for an outboard motor.
Outboard motors are normally powered by two-cycle engines because of the simplicity of these engines. However, there are many instances when it is desirable to employ a four-cycle internal combustion engine as the propulsion unit for an outboard motor. If a four-cycle engine is employed, it is necessary to provide an oil sump for the lubrication system of the engine. If the engine is mounted with its crankshaft extending vertically, as is the normal case with outboard motors, the oil sump is positioned externally of the engine. As is well known, the oil serves a cooling function in addition to a lubricating function. Continuous recycling of the oil during long periods of motor running can, however, cause the oil temperature to rise excessively and reduce the lubricating capabilities of the oil.
It is, therefore, a principal object of this invention to provide an improved lubricating and cooling system for a four-cycle internal combustion engine.
It is a further object of this invention to provide a lubricating system for a four-cycle outboard motor engine wherein the lubricant is cooled.
Because of the compact nature of outboard motors, when a four-cycle engine is employed, the exhaust system normally passes in close proximity to the oil pan or oil sump. As a result of this proximity, there is a danger that the lubricating oil, which as has been already noted is heated during engine operation, may be still further heated.
It is, therefore, a still further object of this invention to provide an improved exhaust and oil sump system for an internal combustion engine.
It is a further object of this invention to provide an exhaust and oil sump system for an outboard motor wherein transmission of heat from the exhaust system to the oil sump is minimized.